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Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.
A dedicated circuit is a data-communication pathway between two communicating systems. The circuit may exist as a physical cable between two systems, or may exist logically within a multiplexed or switched communication network. Dedicated circuits are typically leased lines (permanent links with billing based on distance and capacity. They are typically used to create private WANs (wide area networks). A dedicated circuit is either a voice-grade analog line requiring modems at each end, or a digital line such as a T1-type service that provides transmission speeds up to 1.544 Mbits/sec or a T3 line at 45 Mbits/sec.
A dedicated circuit can also exist logically (as a virtual circuit) in switching networks such as X.25, frame relay, ATM networks, and the Internet. Depending on the network type, the carrier may predefine a path with a guaranteed bandwidth through the network.
Network administrators evaluating the use of these lines must weigh the cost of a leased line based on the amount of traffic that will traverse it and whether an uninterrupted connection must be maintained at all times. If traffic is light, or peaks during parts of the day, a dial-up or circuit-switched line may be better. A dial-up line may also supplement a dedicated circuit by providing occasional transmissions, such as bulk e-mail transfers or replication of server information to a remote office. Dedicated lines are best when traffic is constant and service requirements are immediate.
ISDN (Integrated Services Digital Network) provides temporary dedicated circuit capabilities and allows users to dial any other site. DSL (Digital Subscriber Line) services offer another possibility. Newer metropolitan access services are covered under "MAN (Metropolitan Area Network)" and "Network Access Services."
Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.